Airfield lighting control and monitoring system utilizing fiber optic double loop self healing communications

ABSTRACT

Control and monitoring of airfield lighting from a control tower and other maintenance/supervisory locations uses double loop self healing fiber optic communications circuits to enhances speed of operation even with large and complex airfield lighting system requirements, and significantly increased reliability and operating lifetime thereof. A plurality of local light control and monitoring groups are used, wherein each group has at least one fiber optic communications concentrator that independently communicates with light controllers within the group and the remote supervisory control and monitoring systems in the control tower and other locations. This allows faster control response of the lamps in each of the airfield light fixtures, and monitoring concentration of operational data within each group. Each of the at least one fiber optic concentrators is optically coupled to double loop self healing fiber optic communications backbone circuits coupled to main and backup computer supervisory control systems for redundancy purposes.

RELATED PATENT APPLICATION

This application is a continuation application of and claims priorityunder 35 U.S.C. §120 to U.S. patent application Ser. No. 13/270,843,filed Oct. 11, 2011, and titled “Airfield Lighting Control andMonitoring System Utilizing Fiber Optic Double Loop Self HealingCommunications,” which claims priority to commonly owned U.S.Provisional Patent Application Ser. No. 61/435,074; filed Jan. 21, 2011;entitled “Airfield Lighting Control and Monitoring System UtilizingParallel Fiber Optic Communication,” by Maoz Ohad and Andrei Weintraub;and both of the foregoing applications are hereby incorporated byreference herein for all purposes.

TECHNICAL FIELD

The present invention relates generally to airfield lighting systems,and more particularly, to an airfield lighting control and monitoringsystem utilizing fiber optic double loop self healing communications.

BACKGROUND

The control of aircraft on the ground is a very complicated and highstakes task. Airfields must often provide control and guidance toaircraft while taxiing or standing both before takeoff and afterlanding. Safety and reliability are at a premium in the field ofaircraft control on the ground. For this purpose, airfield lightingcontrol systems have been developed to prevent incursions onto an activerunway or taxiway, thereby reducing the possibility of collisionsbetween aircraft, especially during conditions of low visibility.

Existing airport runways typically include a series of runway lightfixtures secured along the centerline (embedded in the runway) and/orsidelines (embedded or raised) of an airport runway. Each light fixtureincludes one or more light sources, e.g., incandescent, fluorescentand/or light emitting diode (LED) lamps, which provide illumination andpositional guidance to aircraft on the airport runway. Each lightfixture includes one or more lamps that provide illumination andguidance to the aircraft. The runway light fixtures are powered by meansof series connected isolating current transformers fed from a constantcurrent regulator circuit located in an electrical vault near or beneaththe runway. The constant current regulator typically is set at a currentvalue that is selectable in steps from about 2.8 to 6.6 amperes RMS.

Control and monitoring of the runway lights are performed remotely atthe control tower, and also at other maintenance locations. Therebyenabling airport personnel in the control tower to select individuallythe intensity (off being one intensity of zero) of the lightillumination for each runway. In addition, lamps may be controlled toflashed on and off in various patterns.

Remote monitoring of the airfield lighting system is critical for safeoperation. If an excessive number of runway lamps malfunction,especially if adjacent runway lamps malfunction, the lightingconfiguration of the runway may be adversely changed.

To effect remote control and monitoring of the airport lighting from thecontrol tower, and other locations for maintenance and testing purposes,remote control and monitoring devices must be used in combination withthe lighting fixtures, one control circuit for each lamp to becontrolled, and enough monitoring points to insure that the runwaylighting system is operating sufficiently to safely guide and controlmovements of aircraft on the runway(s). Typically, these controlcircuits are located close to or within each associated runway lightfixture. Since electrical power conductors must be used to supply powerto each runway light fixture, a popular and effective way to sendcontrol signals to and receive monitoring/status signals from eachrunway light fixture has been to impress power line carrier signals uponthese electrical power conductors.

Using power line carrier control and monitoring has significantadvantages as substantially less wire has to be run throughout therunway(s), and power line carrier signaling equipment is a maturetechnology that is relatively inexpensive to implement with today'selectronic components. However, power line carrier signaling equipmentsuffers from some very basic and difficult to solve weaknesses (e.g.,vulnerabilities) in systems operations and reliability. Power linecarrier control and monitoring communications depends on the quality ofthe airfield power circuit wiring which is in a constant of degradationand will eventually develop faults. In addition, electricalnoise/interference generated by power switching operations, lightningstrikes and other man made and natural interference at the power linecarrier signal frequencies degrades the operation/monitoring/speed ofthe airfield lighting control system. Also, if a power circuit is brokento a group of light fixtures that is used to feed the carrier signals toother groups of light fixtures, major runway lighting outages may occur.Operational speed of a power line carrier signaling system is alsolimited as the complexity of the runway lighting system increases.Electrical signal noise and interference will also reduce the effectivespeed of operation of the power line carrier signaling system.

SUMMARY

Therefore, what is needed is a more robust and higher speed of operationfor controlling and monitoring airfield lighting systems remotely from acontrol tower and other maintenance/supervisory locations. Using fiberoptic communications to control and monitor operation of airfield lightfixtures eliminates the possibility of cross-talk, signal interference,lightning strike interference and power wiring degradation thatsignificantly affects present technology power line carrier signalingsystems. In addition, a significant advantage in using fiber opticcommunications is enhanced speed of operation even with large andcomplex airfield lighting system requirements, and significantlyincreased reliability and operating lifetime.

According to the teachings of this disclosure, further communicationstime improvements and operational reliability are accomplished byseparating a large serial fiber optic communications circuit into aplurality of smaller fiber optic communications circuit groups. Eachgroup having at least one fiber optic communications concentrator thatindependently communicates with fiber optic signal based light fixturecontrollers within the group and the remote supervisory control andmonitoring systems in the control tower and other locations. This allowsfaster control response of the lamps in each of the airfield lightfixtures, and monitoring concentration of operational data within eachgroup for example, but not limited to, exception (fault, malfunction,etc.) reporting in a background mode that does not impact execution ofcontrol command speeds.

A further improvement in airfield lighting system operationalreliability may be obtained, according to the teachings of thisdisclosure, by utilizing fiber optic double loop self healingcommunications. The fiber optic double loop self healing communicationsmay be provided, as more fully described hereinafter, with a pluralityof light controllers having fiber optic communications capabilities thatare coupled between a main concentrator and a backup concentrator havingfiber optic communications capabilities. In addition, the main andbackup concentrators may also function as light controllers. It iscontemplated and within the scope of this disclosure that the samehardware may be used for both the light controllers and theconcentrators, with differentiation made therebetween by software(firmware) programming.

A local light control and monitoring group using fiber optic double loopself healing communications may therefore be characterized as comprisinga main concentrator (with or without light controller capabilities), aplurality of light controllers and a backup concentrator (with orwithout light controller capabilities). The main concentrator, pluralityof light controllers and backup concentrator communicate using serialdata over light transmissive fiber optic cables. There are two receiveand two transmit fiber optic communications ports associated with eachone of the main and backup concentrators, and the plurality of lightcontrollers. One of these receive ports is associated with one of thetransmit ports, and the other receive port is associated with the othertransmit port such that data received on the one receive port isretransmitted on the one transmit port, and data received on the otherreceive port is retransmitted on the other transmit port. Dataassociated with a particular concentrator or light controller may bedetected (received) from either one or both of the receive ports orinserted (transmitted) into either one or both of the transmit portsassociated with that particular concentrator or light controller.Therefore there are two paths for receive data and two paths fortransmit data (duplex—simultaneous transmit and receive) for each one ofthe concentrators and light controllers, the data received at the onereceive port is repeated through the one transmit port, and the datareceived at the other receive port is repeated through the othertransmit port.

Data not intended for or from a respective concentrator or lightcontroller is merely passed through (repeated) by the main concentrator,plurality of light controllers and/or backup concentrator over the lighttransmissive fiber optic communications cables therebetween. One end ofa local double loop duplex fiber optic communications circuit is coupledto the one receive and transmit ports of the main concentrator. Theother receive and transmit ports of the main concentrator are coupled tothe one transmit and receive ports, respectively, of the first one ofthe plurality of light controllers. The other receive and transmit portsof the first one of the plurality of light controllers are coupled tothe one transmit and receive ports, respectively, of the next one of theplurality of light controllers, etc. Finally the other receive andtransmit ports of the last one of the plurality of light controllers arecoupled to the one transmit and receive ports, respectively, of thebackup concentrator. The other receive and transmit ports of the backupconcentrator are coupled to the other end of the local double loopduplex fiber optic communications circuit. Whereby any one of the mainand backup concentrators and the plurality of light controllers may beaccessed (scanned) by a control system coupled into the local doubleloop duplex fiber optic communications circuit. If some of the pluralityof light controllers are only accessible by the main concentrator andthe other ones of the plurality of light controllers are only accessibleby the backup concentrator, then the control system may stillcommunicate with all of the plurality of light controllers through arespective concentrator (concentrator may also be a light controller)having an operative duplex fiber optic communications circuittherebetween.

For example, if the one end of the local double loop duplex fiber opticcommunications circuit coupled to the main concentrator becomesinoperative, then the control system may use exclusively the other endthe local double loop duplex fiber optic communications circuit coupledto the backup concentrator for communicating with the main concentrator,backup concentrator and/or any one or more of the plurality of lightcontrollers. And visa-versa if the other end of the local double loopduplex fiber optic communications circuit coupled to the backupconcentrator becomes inoperative. In addition, a fiber opticcommunications failure between any one of the plurality of lightcontrollers, or between a main or backup concentrator and a one of theplurality of light controllers may similarly be healed by “going theother way” around the local double loop duplex fiber opticcommunications circuit and through any intervening concentrator and/orlight controllers.

A plurality of local light control and monitoring groups may beimplemented as describe herein, wherein each one of the plurality oflocal light control and monitoring groups may operate independently fromthe others on their respective local double loop duplex fiber opticcommunications circuits. Therefore, scanning and control within each oneof the local lamp control and monitoring groups may be performedindependently of the other, and also done simultaneously (in parallel)for all of these local groups over their respective local double loopduplex fiber optic communications circuits.

The control system is data coupled to each one of the plurality of locallamp control and monitoring groups through a backbone double loop duplexfiber optic communications circuit coupled to a data router that also iscoupled to each one of the local double loop duplex fiber opticcommunications circuits associated with the plurality of local lampcontrol and monitoring groups. The data router is a fiber optic hub ormultiplexer that disseminates data to and from the backbone double loopduplex fiber optic communications circuit and the local double loopduplex fiber optic communications circuits. The data router performs nologic functions and is only hardware that facilitates fiber opticcommunications between the backbone and local double loop duplex fiberoptic communications circuits. Routing logic for addressing data to/fromeach of the plurality of light controllers may be performed by the mainand/or backup concentrators associated with each local group of lightcontrollers.

According to a specific example embodiment of this disclosure, anairfield lighting control and monitoring system comprises: a maincomputer; a backup computer; a main backbone fiber optic to serialinterface, wherein a serial interface portion thereof is coupled to themain computer; a backup backbone fiber optic to serial interface,wherein a serial interface portion thereof is coupled to the backupcomputer; a fiber optic router having a plurality of fiber optictransmit and receive port pairs; a backbone double loop self healingfiber optic communications circuit having a main backbone fiber opticportion and a backup backbone fiber optic portion, wherein a first endof the main backbone fiber optic portion is coupled to a fiber optictransmit and receive port pair of the main backbone fiber optic toserial interface, a second end of the main backbone fiber optic portionis coupled to one of the plurality of fiber optic transmit and receiveport pairs of the fiber optic router, a first end of the backup backbonefiber optic portion is coupled to a fiber optic transmit and receiveport pair of the backup backbone fiber optic to serial interface, and asecond end of the backup backbone fiber optic portion is coupled toanother one of the plurality of fiber optic transmit and receive portpairs of the fiber optic router; a plurality of local light control andmonitoring groups, each of the plurality of local light control andmonitoring groups comprises: a main concentrator having first and secondfiber optic transmit and receive port pairs, a backup concentratorhaving first and second fiber optic transmit and receive port pairs, aplurality of light controllers having first and second fiber optictransmit and receive port pairs, wherein the plurality of lightcontrollers are fiber optically coupled together, the first one of theplurality of light controllers is fiber optically coupled to the mainconcentrator, and the last one of the plurality of light controllers isfiber optically coupled to the backup concentrator; and a local doubleloop self healing fiber optic communications circuit having a main localfiber optic portion and a backup local fiber optic portion, wherein afirst end of the main local fiber optic portion is coupled to a fiberoptic transmit and receive port pair of the main concentrator, a secondend of the main local fiber optic portion is coupled to a respective oneof the plurality of fiber optic transmit and receive port pairs of thefiber optic router, a first end of the backup local fiber optic portionis coupled to a fiber optic transmit and receive port pair of the backupconcentrator, and a second end of the backup local fiber optic portionis coupled to another respective one of the plurality of fiber optictransmit and receive port pairs of the fiber optic router; wherein themain and backup computers can communicate with any one or more of theplurality of light controllers through the backbone double loop selfhealing fiber optic communications circuit, the fiber optic router,respective ones of the local double loop self healing fiber opticcommunications circuits, and respective ones of the main or backupconcentrators.

According to another specific example embodiment of this disclosure, alocal light control and monitoring group comprises: a main concentratorhaving first and second fiber optic transmit and receive port pairs, abackup concentrator having first and second fiber optic transmit andreceive port pairs, a plurality of light controllers having first andsecond fiber optic transmit and receive port pairs, wherein theplurality of light controllers are fiber optically coupled together, thefirst one of the plurality of light controllers is fiber opticallycoupled to the main concentrator, and the last one of the plurality oflight controllers is fiber optically coupled to the backup concentrator;and a local double loop self healing fiber optic communications circuithaving a main local fiber optic portion and a backup local fiber opticportion, wherein a first end of the main local fiber optic portion iscoupled to a fiber optic transmit and receive port pair of the mainconcentrator, a second end of the local backbone fiber optic portion iscoupled to a fiber optic router, a first end of the backup local fiberoptic portion is coupled to a fiber optic transmit and receive port pairof the backup concentrator, and a second end of the backup local fiberoptic portion is coupled to the fiber optic router; wherein any one ormore of the plurality of light controllers, and main and backupconcentrators are accessible from the main or backup local fiber opticportions of the local double loop self healing fiber opticcommunications circuit.

According to yet another specific example embodiment of this disclosure,a method for control and monitoring of an airfield lighting systemcomprises the steps of: providing at least one computer having main andbackup fiber optic transmit and receive port pairs; providing a fiberoptic router having a plurality of fiber optic transmit and receive portpairs; providing a backbone double loop self healing fiber opticcommunications circuit having a main backbone fiber optic portion and abackup backbone fiber optic portion, wherein the backbone double loopself healing fiber optic communications circuit comprises the steps of:coupling a first end of the main backbone fiber optic portion to a fiberoptic transmit and receive port pair of the main backbone fiber optic toserial interface, coupling a second end of the main backbone fiber opticportion to one of the plurality of fiber optic transmit and receive portpairs of the fiber optic router, coupling a first end of the backupbackbone fiber optic portion to a fiber optic transmit and receive portpair of the backup backbone fiber optic to serial interface, andcoupling a second end of the backup backbone fiber optic portion toanother one of the plurality of fiber optic transmit and receive portpairs of the fiber optic router; providing a plurality of local lightcontrol and monitoring groups, each of the plurality of local lightcontrol and monitoring groups comprises: a main concentrator havingfirst and second fiber optic transmit and receive port pairs, a backupconcentrator having first and second fiber optic transmit and receiveport pairs, a plurality of light controllers having first and secondfiber optic transmit and receive port pairs, wherein the plurality oflight controllers are fiber optically coupled together, the first one ofthe plurality of light controllers is fiber optically coupled to themain concentrator, and the last one of the plurality of lightcontrollers is fiber optically coupled to the backup concentrator; and alocal double loop self healing fiber optic communications circuit havinga main local fiber optic portion and a backup local fiber optic portion,wherein the local double loop self healing fiber optic communicationscircuit comprises the steps of: coupling a first end of the main localfiber optic portion to a fiber optic transmit and receive port pair ofthe main concentrator, coupling a second end of the main local fiberoptic portion to a respective one of the plurality of fiber optictransmit and receive port pairs of the fiber optic router, coupling afirst end of the backup local fiber optic portion to a fiber optictransmit and receive port pair of the backup concentrator, and couplinga second end of the backup local fiber optic portion to anotherrespective one of the plurality of fiber optic transmit and receive portpairs of the fiber optic router; and communicating with the at least onecomputer to any one or more of the plurality of light controllersthrough the backbone double loop self healing fiber optic communicationscircuit, the fiber optic router, respective ones of the local doubleloop self healing fiber optic communications circuits, and respectiveones of the main or backup concentrators.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and theadvantages thereof, reference is now made to the following description,in conjunction with the accompanying drawings briefly described asfollows.

FIG. 1 illustrates a schematic block diagram of an airfield lightingcontrol and monitoring system utilizing a backbone and a plurality oflocal fiber optic double loop self healing communications circuits,according to a specific example embodiment of this disclosure;

FIG. 2 illustrates a more detailed schematic block diagram of the mainand backup computer portion of the airfield lighting control andmonitoring system shown in FIG. 1;

FIG. 3 illustrates a more detailed schematic block diagram of a locallamp control and monitoring group, an associated local double loopduplex fiber optic communications circuit and an associated mainconcentrator shown coupled to a fiber optic communications router,according to the specific example embodiment of FIG. 1;

FIG. 4 illustrates a more detailed schematic block diagram of anotherlocal lamp control and monitoring group, an associated local double loopduplex fiber optic communications circuit and an associated backupconcentrator coupled to a fiber optic communications router, accordingto the specific example embodiment of FIG. 1; and

FIG. 5 illustrates a schematic block diagram of a lightcontroller/concentrator of the airfield lighting control and monitoringsystem shown in FIG. 1, according to a specific example embodiment ofthis disclosure.

While the present disclosure is susceptible to various modifications andalternative forms, specific example embodiments thereof have been shownin the drawings and are herein described in detail. It should beunderstood, however, that the description herein of specific exampleembodiments is not intended to limit the disclosure to the particularforms disclosed herein, but on the contrary, this disclosure is to coverall modifications and equivalents as defined by the appended claims.

DETAILED DESCRIPTION

Referring now to the drawings, details of specific embodiments of thepresent invention are schematically illustrated. Like elements in thedrawings will be represented by like numbers, and similar elements willbe represented by like numbers with a different lower case lettersuffix.

Referring to FIG. 1, depicted is a schematic block diagram of anairfield lighting control and monitoring system utilizing a backbone anda plurality of local fiber optic double loop self healing communicationscircuits, according to a specific example embodiment of this disclosure.The airfield lighting control and monitoring system (hereinafter“ALCMS”), generally represented by the numeral 100, comprises a maincomputer 102, a backup computer 104, a main backbone fiber optic toserial interface 106, a backup backbone fiber optic to serial interface108, a plurality of fiber optic routers 110, a plurality of local lightcontrol and monitoring groups 112, a backbone fiber optic double loopself healing communications circuit (120, 122, 124); and a plurality oflocal fiber optic double loop self healing communications circuits (130,132). The serial interface portions of the main and backup backbonefiber optic to serial interfaces 106 and 108 may be full duplex serialdata communications such as, for example but not limited to, RS-422/485,Ethernet, USB, Firewire, etc. It is contemplated and within the scope ofthis disclosure that the main computer 102 and backup computer 104 maybe combined into, for example but not limited to, one high reliabilitycomputer having two serial interfaces available to couple to the mainbackbone fiber optic to serial interface 106 and the backup backbonefiber optic to serial interface 108.

The backbone fiber optic double loop self healing communications circuitcomprises main backbone loop circuits 120, backup backbone loop circuits122, and a transition backbone loop circuit 124. The plurality of localfiber optic double loop self healing communications circuits eachcomprise main local loop circuits 130 and backup local loop circuits132. These double loop self healing communications circuits are coupledtogether for communications therebetween by means of the plurality offiber optic routers 110 as more fully disclosed hereinafter. Data, e.g.,monitoring and control, communications may be by using serial digitaltime division multiplexing (TDM) of data bytes or packets as used inEthernet communications systems and the like. Generally, data flowsbetween the backbone double loop circuit (120, 122, 124) and eachindividual local double loop circuit (130, 132) so that the computers102, 104 can monitor and issue control commands to each point (light) inthe local light control and monitoring groups 112. However, it iscontemplated and within the scope of this disclosure that different onesof the plurality of local light control and monitoring groups 112 maycommunicate with each other over their respective individual localdouble loop circuits (130, 132).

The plurality of fiber optic routers 110 are coupled together tofunction as a fiber optic hub or multiplexer that spreads or routs databetween the backbone double loop circuit (120, 122, 124) and theindividual local double loop circuits (130, 132). The backbone doubleloop circuit (120, 122, 124) comprises a duplex or half duplex fiberoptic communications cable, e.g., a plurality of conductive glass orplastic fibers conducting light wavelengths, providing duplex, halfduplex and/or simplex light wave communications paths between fiberoptic interfaces. Each of the fiber optic routers 110 can alsocommunicate with an adjacent fiber optic router 110, for example overfiber optic duplex communications cables 120, 120 a, 122, 122 a and 124.Wherein if one of the fiber optic duplex communications paths (cables120, 120 a, 122, 122 a and 124) to a fiber optic router 110 shouldmalfunction, then that fiber optic router 110 can still remainfunctional with the other connected fiber optic duplex communicationspath (cable). This fiber optic communications configuration is referredto as “double loop self healing communications” since there are twocommunications paths represented by the main backbone loop circuits 120,backup backbone loop circuits 122, and a transition backbone loopcircuit 124 therebetween. If one of these communications circuits shouldfail, either the main computer 102 or the backup computer 104 can stillcommunicate with any of the fiber optic routers 110 over either the mainbackbone loop circuit 120 or the backup backbone loop circuit 122,respectively. The main computer 102 and the backup computer 104 alsocommunicate and synchronize operations over communications link 140.Thus either or both of the computers 102, 104 can control the ALCMS 100.These fiber optic communications cables (120, 122, 124, 130, 132) may belocated in electrical conduit, armor sheaving, and/or direct burialcables. Each of the fiber optic routers 110 further communicates withthe plurality of local light control and monitoring groups 112, asdescribed more fully hereinbelow.

Referring to FIG. 2, depicted is a more detailed schematic block diagramof the main and backup computer portion of the airfield lighting controland monitoring system shown in FIG. 1. The main computer 102communicates with the first backbone fiber optic to serial interface106, and the backup computer 104 communicates with the second backbonefiber optic to serial interface 108, over full duplex copper serial datacommunications cables such as those used with for example, but notlimited to, RS-422/485, Ethernet, USB, Firewire, etc. The main andbackup backbone fiber optic to serial interfaces 106 and 108 convert theelectrical data signals from the main and backup computers 102 and 104,respectively, to light wave signals for transmission in the fiber opticcables comprising the main and backup fiber optic backbone circuits 120and 122, respectively, that comprise the backbone fiber optic doubleloop circuit. A health, synchronization and/or failover communicationslink 140 may be used between the main computer 102 and the backupcomputer 104 for synchronization and/or automatic failover purposesduring operation and/or a fault condition in either one of thesecomputers, or upon a failure in either the main and backup fiber opticbackbone circuits 120 and 122. The fiber optic to serial interfaces maybe, for example but are not limited to, a Model 2140 Optical MiniBit-Driver® (a registered trademark of S.I. Tech, P.O. Box 609, Geneva,Ill. 60134), www.sitech-bitdriver.com, incorporated by reference herefor all purposes. The functions of the main and backup backbone fiberoptic to serial interfaces 106 and 108 are repeating data between thefiber optic ports and to drop/insert data on the RS-422/485 port. TheRS-422/485 port can insert data onto both fiber ports and drop data fromboth fiber ports.

Referring to FIG. 3, depicted is a more detailed schematic block diagramof a local lamp control and monitoring group, an associated local doubleloop duplex fiber optic communications circuit and an associated mainconcentrator shown coupled to a fiber optic communications router,according to the specific example embodiment of FIG. 1. One fiber opticrouter 110 a of the plurality of fiber optic routers 110 is showncoupled to the main fiber optic backbone 120 (e.g., fiber optic cable).Each of the fiber optic routers 110 (110 a shown as an example)comprises a fiber optic to serial interface 312 and a plurality of fiberoptic to serial interfaces 310. These fiber optic to serial interfacesmay be, for example but are not limited to, a Model 2140 Optical MiniBit-Driver® (a registered trademark of S.I. Tech, P.O. Box 609, Geneva,Ill. 60134), www.sitech-bitdriver.com, incorporated by reference herefor all purposes.

The purpose of the fiber optic to serial interfaces 310 and 312 are forrepeating data between the fiber optic ports and to drop/insert data onthe RS-422/485 ports. The RS-422/485 port can insert data onto bothfiber ports and drop data from both fiber ports. The RS-422/485 portsare tied together so as to enable intercommunications between the fiberoptic to serial interfaces 310 and 312, and devices connected thereto. Aserial switch 314 (Ethernet router) is optionally shown if Ethernetinterfaces are used in the fiber optic to serial interfaces 310 and 312instead of RS-422/485. However, operation remains the same. The fiberoptic to serial interface 312 a optically couples (the RS-422/485 portsare electrically coupled together) the main backbone circuit 120 to thefiber optic router 110 a.

Each of the plurality of fiber optic to serial interfaces 310 isconnected to a respective one of the local light control and monitoringgroups 112 with main local loop circuits 130. Shown in FIG. 3 is arepresentative local light control and monitoring group 112 a comprisinga main concentrator 330 a, a backup concentrator 332 a, a plurality oflight controllers 334, a plurality of current transformers 340, and aconstant current regulator 342. The main concentrator 330 a is connectedto the fiber optic to serial interface 310 a of the fiber optic router110 a with a fiber optic duplex communications cable comprising the mainlocal loop circuit 130 a. The backup concentrator 332 a is connected toa fiber optic to serial interface 310 of a fiber optic router 110 m(FIG. 1) with a fiber optic duplex communications cable comprising thebackup local loop circuit 132 a.

Control and status information is optically coupled between the mainconcentrator 330 a and the light controller 334 m, and the backupconcentrator 332 a and the light controller 334 b. Also this control andstatus information is optically coupled between the plurality of lightcontrollers 334 b-334 m. Whereby two fiber optic communications pathsare available, a main and a backup configured as a local fiber opticdouble loop self healing communications circuit. The fiber optic passthrough communications feature of the concentrators 330 a and 332 a, andthe plurality of light controllers 334 b-334 m enable redundant controland monitoring with a high level of availability and increasedreliability of the airfield lighting system, according to the teachingsof this disclosure. The main and backup concentrators 330 and 332 mayalso comprise light controllers as more fully disclose in FIG. 5 and thedescription therewith.

The plurality of current transformers 340 supply isolated operatingpower to respective ones of the plurality of light controllers 334 andconcentrators 330 and 332 for operational control of and power toairfield runway lighting. Each current transformer 340 may have, forexample but is not limited to, a capacity of from about 40 watts toabout 600 watts of power. A constant current regulator 342 suppliespower at a constant current to the current transformers 340. A value forthis constant current may be selectable, e.g., from about 2.8 amperes toabout 6.6 amperes RMS. A plurality of airfield runway lights 344 and 346are controlled by respective ones of the light controllers 334. The mainand backup concentrators 330 and 332 may also include light controlcircuits like in the light controllers 334, and therefore may alsocontrol some of the airfield runway lights 344 and 346. It iscontemplated and within the scope of this disclosure that the samehardware may be used for both the light controllers 334 and theconcentrators 330 and 332, with differentiation made therebetween bysoftware (firmware) programming.

Referring to FIG. 4, depicted is a more detailed schematic block diagramof another local lamp control and monitoring group, an associated localdouble loop duplex fiber optic communications circuit and an associatedbackup concentrator coupled to a fiber optic communications router,according to the specific example embodiment of FIG. 1. One fiber opticrouter 110 n of the plurality of fiber optic routers 110 is showncoupled to the backup fiber optic backbone 122 (e.g., fiber opticcable). Each of the fiber optic routers 110 (110 n shown as an example)comprises a fiber optic to serial interface 412 and a plurality of fiberoptic to serial interfaces 410. These fiber optic to serial interfacesmay be, for example but are not limited to, a Model 2140 Optical MiniBit-Driver® (a registered trademark of S.I. Tech, P.O. Box 609, Geneva,Ill. 60134), www.sitech-bitdriver.com, incorporated by reference herefor all purposes.

The purpose of the fiber optic to serial interfaces 410 and 412 are forrepeating data between the fiber optic ports and to drop/insert data onthe RS-422/485 ports. The RS-422/485 port can insert data onto bothfiber ports and drop data from both fiber ports. The RS-422/485 portsare tied together so as to enable intercommunications between the fiberoptic to serial interfaces 410 and 412, and devices connected thereto. Aserial switch 414 (Ethernet router) is optionally shown if Ethernetinterfaces are used in the fiber optic to serial interfaces 410 and 412instead of RS-422/485. However, operation remains the same. The fiberoptic to serial interface 412 a optically couples (the RS-422/485 portsare electrically coupled together) the backup backbone circuit 122 tothe fiber optic router 110 n.

Each of the plurality of fiber optic to serial interfaces 410 isconnected to a respective one of the local light control and monitoringgroups 112 with backup local loop circuits 132. Shown in FIG. 4 is arepresentative local light control and monitoring group 112 p comprisinga main concentrator 430 a, a backup concentrator 432 a, a plurality oflight controllers 434, a plurality of current transformers 440, and aconstant current regulator 442. The backup concentrator 432 a isconnected to fiber optic to serial interface 410 c of the fiber opticrouter 110 n with a fiber optic duplex communications cable comprisingthe backup local loop circuit 132 p. The main concentrator 430 a isconnected to the fiber optic to serial interface 310 c of a fiber opticrouter 110 m-l (FIG. 1) with the fiber optic duplex communications cablecomprising the main local loop circuit 130 p.

Control and status information is optically coupled between the backupconcentrator 432 a and the light controller 434 b, and the mainconcentrator 430 a and the light controller 434 m. Also this control andstatus information is optically coupled between the plurality of lightcontrollers 434 b-434 m. Whereby two fiber optic communications pathsare available, a main and a backup configured as a local fiber opticdouble loop self healing communications circuit. The fiber optic passthrough communications feature of the concentrators 430 a and 432 a, andthe plurality of light controller 434 b-434 m enable redundant controland monitoring with a high level of availability and increasedreliability of the airfield lighting system, according to the teachingsof this disclosure. The main and backup concentrators 430 and 432 mayalso comprise light controllers as more fully disclose in FIG. 5 and thedescription therewith.

The plurality of current transformers 440 supply isolated operatingpower to respective ones of the plurality of light controllers 434 andconcentrators 430 and 432 for operational control of and power toairfield runway lighting. Each current transformer 440 may have, forexample but is not limited to, a capacity of from about 40 watts toabout 600 watts of power. A constant current regulator 442 suppliespower at a constant current to the current transformers 440. A value forthis constant current may be selectable, e.g., from about 2.8 amperes toabout 6.6 amperes RMS. A plurality of airfield runway lights 444 and 446are controlled by respective ones of the light controllers 434. The mainand backup concentrators 430 and 432 may also include light controlcircuits like in the light controllers 434, and therefore may alsocontrol some of the airfield runway lights 444 and 446. It iscontemplated and within the scope of this disclosure that the samehardware may be used for both the light controllers 434 and theconcentrators 430 and 432, with differentiation made therebetween bysoftware (firmware) programming.

Referring to FIG. 5, depicted is a schematic block diagram of a lightcontroller/concentrator of the airfield lighting control and monitoringsystem shown in FIG. 1, according to a specific example embodiment ofthis disclosure. A fiber optic light controller and concentrator 530comprises a digital processor 550, random access memory (RAM) andprogrammable nonvolatile memory 552, a fiber optic to serial interface554, a serial interface 556, lamp drivers and burnt-out lamp detectioncircuits 558, and a direct current (DC) power supply 560. The fiberoptic light controller and concentrator 530 may also be configured as afiber optic light controller (e.g., controllers 334 and 434) by a simplefirmware change that disables the concentrator functions thereof. Thisfacilitates reducing the different types of products manufactured andthe number of spares required at an airfield installation. A simplefield programming change may configure the fiber optic light controllerand concentrator 530 for lamp control only, or lamp control and dataconcentration.

General operation of the fiber optic light controller and concentrator530 may be, for example but is not limited to, control of one or twolamps, e.g., lamps 544 and 546, with the controller and concentrator 530located between the lamp(s) 544 and 546, and a secondary (power circuit568) of a respective one of the current transformers 340 or 440. Thecontroller and concentrator 530 has the capabilities of operatingdifferent light fixtures and/or functions. For example, but not limitedto, failed lamp location (FLL), in-pavement runway guard lights (IRGL),elevated runway guard lights (ERGL), stop bar, dual lamps, center linelamps, sensors (e.g., intrusion, temperature, water/ice, etc.),switching and command, e.g., burnt out lamp (BOL) detection, lampstatus, flashing of lamps, etc. The lamps may be switched on and offwith mechanical or solid state relays, and the lamps may be flashed onand off using solid state relays or other devices, e.g., a triac. Aburnt out lamp may be shorted out of the series connected circuit with arelay (not shown) so that the other or backup lamp may still operate.Control commands, operational profiles and status may be stored in thedata concentrator portion of the controller and concentrator 530. Lampactivation and monitoring may be available from an airfield controltower, power control vault and/or maintenance room (not shown).

The digital processor 550 is coupled to a serial programming port 566with the serial interface 556. A programmer (not shown) may be coupledto the serial interface and then used to program the fiber optic lightcontroller and concentrator 530 to function as either a controller andconcentrator, or just a controller as required. The desired programmingconfiguration(s) may be stored in the nonvolatile portion of thememories 552 along with the operation program that controls theprocessor 550. The processor 550 controls operation of the lamp driversand may receive lamp status from the lamp drivers and burnt-out lampdetection 558, as disclosed more fully hereinabove. The processor 550also communicates with the fiber optic to serial interface 554 duringnormal operation of the fiber optic light controller and concentrator530.

The fiber optic to serial interface 554 has an upstream optical dataport 562 and a downstream optical data port 564. Optically encodeddigital information can pass (e.g., exchanged) between these two opticaldata port 562 and 564. An electronic communications bus 570 is coupledto the processor 550 so that the processor 550 can retrieve informationfrom and/or inject information into either one or both of the opticaldata ports 562 and 564. The processor 550 may thereby communicate with arespective fiber optic router 110 and/or an adjacent main or backupconcentrators 330, 332 or 430, 432. The fiber optic to serial interface554 has two possible data paths that may be used concurrently orindependently with the processor 550, and affords communicationsredundancy with the main computer 102 and/or backup computer 104. Also,control to and status information from the main or backup concentrator330, 332 or 430, 432 may be stored (e.g., concentrated) in either one orboth of the main (330 or 430) and/or backup (332 or 432) concentratorsassociated with the group 112 (FIG. 1). This feature of the inventionenables faster parallel/redundant operation of both control and statusretrieval since each group 112 may operate independently of another.Concentration of information provided by the main and/or backupconcentrators further improves response time speeds because bursts ofaccumulated historical information may be retrieved at one time insteadof just receiving bits of information on a piece meal basis. Exceptionstatus reporting may further improve throughput and response times. Aplurality of control commands for different ones of the main and/orbackup concentrators, e.g., 330, 332, of a group 112 may be sent to anappropriate one or both concentrators of that group 112 for subsequentindependent distribution to the appropriate light controllers, e.g.,334, of that group 112.

Although specific example embodiments of the invention have beendescribed above in detail, the description is merely for purposes ofillustration. It should be appreciated, therefore, that many aspects ofthe invention were described above by way of example only and are notintended as required or essential elements of the invention unlessexplicitly stated otherwise. Various modifications of, and equivalentsteps corresponding to, the disclosed aspects of the exemplaryembodiments, in addition to those described above, can be made by aperson of ordinary skill in the art, having the benefit of thisdisclosure, without departing from the spirit and scope of the inventiondefined in the following claims, the scope of which is to be accordedthe broadest interpretation so as to encompass such modifications andequivalent structures.

We claim:
 1. An airfield lighting control and monitoring system, saidsystem comprising: a main computer; a backup computer; a first fiberoptic router having a plurality of fiber optic transmit and receive portpairs; a backbone double loop self healing fiber optic communicationscircuit having a main backbone fiber optic portion and a backup backbonefiber optic portion, wherein a first end of the main backbone fiberoptic portion is in communication with the main computer, a second endof the main backbone fiber optic portion is in communication with thefirst fiber optic router, a first end of the backup backbone fiber opticportion is in communication with the backup computer, and a second endof the backup backbone fiber optic portion is in communication with asecond fiber optic router; a plurality of local light control andmonitoring groups, each of the plurality of local light control andmonitoring groups comprises: a main concentrator having first and secondfiber optic transmit and receive port pairs, a backup concentratorhaving first and second fiber optic transmit and receive port pairs, aplurality of light controllers having first and second fiber optictransmit and receive port pairs, wherein the plurality of lightcontrollers are fiber optically coupled together, the first one of theplurality of light controllers is fiber optically coupled to the mainconcentrator, and the last one of the plurality of light controllers isfiber optically coupled to the backup concentrator; and a local doubleloop self healing fiber optic communications circuit having a main localfiber optic portion and a backup local fiber optic portion, wherein afirst end of the main local fiber optic portion is coupled to a fiberoptic transmit and receive port pair of the main concentrator, a secondend of the main local fiber optic portion is coupled to a respective oneof the plurality of fiber optic transmit and receive port pairs of thefirst fiber optic router, a first end of the backup local fiber opticportion is coupled to a fiber optic transmit and receive port pair ofthe backup concentrator, and a second end of the backup local fiberoptic portion is coupled to another respective one of the plurality offiber optic transmit and receive port pairs of the second fiber opticrouter; wherein the main and backup computers can communicate with anyone or more of the plurality of light controllers.
 2. The airfieldlighting control and monitoring system according to claim 1, wherein thefirst fiber optic router comprises: a plurality of fiber optic to serialinterfaces, each of the plurality of fiber optic to serial interfaceshaving first and second transmit and receive fiber optic port pairs anda transmit and receive serial port pair; wherein the transmit andreceive serial port pairs thereof are coupled together such that digitalinformation can be transferred between any two or more of the transmitand receive serial port pairs, digital information can be transferredbetween the first and the second transmit and receive fiber optic portpairs, and digital information can be transferred between the transmitand receive serial port pair and the first or the second transmit andreceive fiber optic port pairs; the first or second transmit and receivefiber optic port pairs of one of the plurality of fiber optic to serialinterfaces of the first fiber optic router is coupled to the second endof the main backbone fiber optic portion of the backbone double loopself healing fiber optic communications circuit; and each of the secondends of the main local fiber optic portions of the local double loopself healing fiber optic communications circuits is coupled to the firstor second fiber optic port pairs of a respective one of the plurality offiber optic to serial interfaces of the first fiber optic router.
 3. Theairfield lighting control and monitoring system according to claim 2,further comprising a serial switch for coupling together the transmitand receive serial port pairs of the plurality of fiber optic to serialinterfaces.
 4. The airfield lighting control and monitoring systemaccording to claim 2, wherein the fiber optic router comprises aplurality of fiber optic routers, wherein each of the plurality of fiberoptic routers comprises a portion of the plurality of fiber optic toserial interfaces.
 5. The airfield lighting control and monitoringsystem according to claim 2, wherein the transmit and receive serialport pairs of the plurality of fiber optic to serial interfaces areRS-422/485 compatible.
 6. The airfield lighting control and monitoringsystem according to claim 1, wherein the main computer communicates withthe main backbone fiber optic portion via a fiber optic to serialinterface.
 7. The airfield lighting control and monitoring systemaccording to claim 6, wherein a serial interface portion of the fiberoptic to serial interface is selected from the group consisting ofEthernet, USB and Firewire compatible interfaces.
 8. The airfieldlighting control and monitoring system according to claim 1, whereineach of the plurality of local light controllers controls at least oneairfield light.
 9. The airfield lighting control and monitoring systemaccording to claim 8, wherein the at least one airfield light isselected from the group consisting of in-pavement runway guard light(IRGL), elevated runway guard light (ERGL), stop bar light, and centerline lights.
 10. The airfield lighting control and monitoring systemaccording to claim 1, further comprising each of the main and backupconcentrators controls at least one airfield light.
 11. The airfieldlighting control and monitoring system according to claim 1, whereineach of the main and backup concentrators, and the plurality of lightcontrollers comprise: a digital processor; random access memory coupledto the digital processor; programmable nonvolatile memory coupled to thedigital processor; first and second fiber optic transmit and receiveport pairs to a transmit and receive serial port pair coupled to thedigital processor; a programming and maintenance serial interface portcoupled to the digital processor; lamp drivers; burnt-out lampdetection; and a power supply.
 12. The airfield lighting control andmonitoring system according to claim 11, wherein the main and backupconcentrators further comprise a program for storing and forwardingstatus information from and commands to the plurality of lightcontrollers.
 13. The airfield lighting control and monitoring systemaccording to claim 11, wherein the first and second fiber optic transmitand receive port pairs can transfer digital information therebetween,and to and from the transmit and receive serial port pair.
 14. Theairfield lighting control and monitoring system according to claim 1,wherein the main and backup computers comprise one computer having mainand backup serial interfaces.
 15. A method for control and monitoring ofan airfield lighting system, said method comprising the steps of:providing at least one computer system having a main interface and abackup interface; providing a first fiber optic router having aplurality of fiber optic transmit and receive port pairs; providing abackbone double loop self healing fiber optic communications circuithaving a main backbone fiber optic portion and a backup backbone fiberoptic portion, wherein the backbone double loop self healing fiber opticcommunications circuit comprises the steps of: coupling a first end ofthe main backbone fiber optic portion to the main interface, coupling asecond end of the main backbone fiber optic portion to one of theplurality of fiber optic transmit and receive port pairs of a firstfiber optic router, coupling a first end of the backup backbone fiberoptic portion to the backup interface, and coupling a second end of thebackup backbone fiber optic portion to one of a plurality of fiber optictransmit and receive port pairs of a second fiber optic router;providing a plurality of local light control and monitoring groups, eachof the plurality of local light control and monitoring groups comprises:a main concentrator having first and second fiber optic transmit andreceive port pairs, a backup concentrator having first and second fiberoptic transmit and receive port pairs, a plurality of light controllershaving first and second fiber optic transmit and receive port pairs,wherein the plurality of light controllers are fiber optically coupledin series, the first one of the plurality of light controllers is fiberoptically coupled to the main concentrator, and the last one of theplurality of light controllers is fiber optically coupled to the backupconcentrator; and a local double loop self healing fiber opticcommunications circuit having a main local fiber optic portion and abackup local fiber optic portion, wherein the local double loop selfhealing fiber optic communications circuit comprises the steps of:coupling a first end of the main local fiber optic portion to a fiberoptic transmit and receive port pair of the main concentrator, couplinga second end of the main local fiber optic portion to a respective oneof the plurality of fiber optic transmit and receive port pairs of thefirst fiber optic router, coupling a first end of the backup local fiberoptic portion to a fiber optic transmit and receive port pair of thebackup concentrator, and coupling a second end of the backup local fiberoptic portion to another respective one of the plurality of fiber optictransmit and receive port pairs of the second fiber optic router; andcommunicating with the at least one computer system to any one or moreof the plurality of light controllers.